What numeric value of b will produce a 45° deflection from north in a region where Earth's magnetic field is 5 × 10⁻⁵ T?
a) 2.5 × 10⁻⁵ T
b) 4.5 × 10⁻⁵ T
c) 6.5 × 10⁻⁵ T
d) 8.5 × 10⁻⁵ T